Saw the Barris Batmobile at a car show once -- absolutely stunning. It was based on the Ford Futura, if I recall, and I thought it took him more than 10 days to create. Many of us kids who watched reruns of the show definitely took it seriously, just as many in the audience took Burton's "Batman" seriously in 1989.
"Star Trek" followed a design philosophy more in line with 1950s movie sci-fi and the pulps of the 20s than, say, "2001's" more realistic (but sterile) sensibility. My parents walked out of that movie in 1968, saying it was not only boring but was like looking at an ad for IBM for 30 minutes. They still couldn't watch it on video 20 years later.
For all of the yakking that goes on here about how fans shouldn't dictate what "Star Trek" looks like or is about, my parents' experience (mirrored by perhaps thousands more that resulted in "2001" being a commercial flop) suggests that sometimes the masses do indeed want something more alive and colorful than what excites the hardcore sci-fi geeks. Say what you will about the original "Star Trek," but it was definitely more alive and colorful than the tedious incarnations that followed.
Is it necessary to keep the design aesthetic of "Star Trek" for what amounts to a prequel? No. But obviously it worked on quite a few people who responded positively to the show. Now that the 1960s mod styles and 1970s counterculture styles are the rage, I'm not sure that the retro sensibility won't work on audiences, assuming Paramount doesn't wait until the fads change to finally release the movie. It is getting into the prequel game awfully late. Chances are the people who will find the look un-hip are, well, nerds, who never seem to understand fashion, and oldsters still cling to the 1980s sensibility of the show with the British bald guy.